View full sizeTwenty-seven balloons were released on Dec. 22 in Mansfield Township in honor of those murdered on Dec. 14 in Newtown, Conn. Hackettstown, Independence, Oxford, Washington Township fire departments as well as the four Mansfield Fire Departments and police and emergency squads to participated.Photo courtesy of Jeff Marchioni

As balloons rose last month in memory of those killed at Sandy Hook Elementary School, so did the blood pressure of environmentalists around the country.

Latex, or rubber balloons, are less expensive than foil balloons, which are made of metalized nylon film, according to the Clean Virginia Waterways website. The balloon's attachments, including plastic disks or clips used to seal the helium, plastic valves and ribbons also are a cause for concern.

Noah Lichtman, spokesman for The Balloon Council, a lobbying group based in Trenton and Washington, D.C., said that properly releasing latex balloons is "a moving and safe use for a memorial commemoration."

"Latex balloons are a fully biodegradable, 100 percent natural product made from the milky sap of a rubber tree," he wrote in an email.

Register said sea turtles and seagulls can become entangled in the ribbons, and that latex balloons are not environmentally friendly, even though they're biodegradable, when animals are exposed to them.

"And the research my organization has done find that most balloon releases do include plastic attachments," she said. "They're still a threat."

Lichtman said The Balloon Council has developed standards for balloon releases in order to minimize their impact on the environment, including the use of self-tied, biodegradable balloons without attachments. He added that when a balloon is properly released into the atmosphere, most rise approximately five miles until the cold air causes them to burst into countless small pieces.

Register says they haven't found that balloons burst and return to the Earth's surface in pieces.

"We find a lot of balloons do come back to Earth not burst, but just deflated, which presents another hazard to animals that mistake a balloon for food," she said.

Three states currently restrict balloon launches: Connecticut, Florida and Virginia. Virginia prohibits 50 or more balloons released in an hour in any one location. The others allow no more than 10, a limit similar to a bill proposed in the New Jersey legislature in 1991 that fell by the wayside.